A believer will not remain in the Fire eternally. If someone dies having committed major sins, other than Shirk (associating others with Allah in His Divinity or worship), without having performed Tawbah (repentance to Allah) for them, it will be left to the Will of Allah to decide. If Allah so wills, they may be punished or forgiven, but their final destination will be to Paradise. Allah (Exalted be He) says:
Verily, Allâh forgives not that partners should be set up with Him (in worship), but He forgives except that (anything else) to whom He wills
Anyone who abandons Salah is a Kafir (disbeliever) and is committing a major act of Kufr (disbelief), on account of which they will abide eternally in the Fire with the other Kafirs.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.